Molecular Epidemiological Monitoring of Circulation of Coxsackievirus A10

Background: Coxsackievirus A10 (CV-A10) is currently one of the most common etiological agents of enterovirus infection (EVI). Over the past decade, severe and fatal cases of CV-A10 infection have become more frequent while clinical manifestations of the disease are similar to those of Enterovirus A71 infection. The objective of our study was to characterize circulation of Coxsackievirus A10 in the Russian Federation in 2008–2019 and to study the phylogenetic relationships of strains isolated in Russia and Vietnam. Materials and methods: In 2008–2019, 220 CV-A10 strains were isolated from patients with various clinical manifestations of EVI and from sewage water samples taken in the Russian Federation and then studied using molecular genetic methods. In addition to that, we analyzed 26 CV-A10 strains isolated from patients with hand, foot, and mouth disease (HFMD) and acute flaccid paralysis in South Vietnam in 2018–2019. Results: We established a two-year periodicity of CV-A10 active circulation in Russia. In the structure of clinical forms of CV-A10 infection, herpetic angina prevailed (30.8 %), followed by minor illness (25.25 %), respiratory diseases (15.66 %), exanthema (14.65 %), gastrointestinal disorders (8.08 %), and asymptomatic infections (2.02 %). Symptoms of CNS damage (meningitis, meningoencephalitis) were observed in 3.53 % of cases. Most CV-A10 strains from Vietnam were isolated from patients with CNS affection of varying degrees of severity. During the study period, CV-A10 strains of genotypes C, E, and F3 circulated in the territory of the Russian Federation whereas the strains from South Vietnam were represented by genotypes F3 and F1. The studied strains showed a genetic relationship with those of CV-A10 circulating in different countries. Vietnamese and some Russian strains of the F3 genotype were genetically close to the strains isolated from severe cases. Conclusions: Molecular monitoring of CV-A10 circulation is an important component of the global epidemiological surveillance of EVI.